This is a revised application requesting continuation of support for a study of irritable bowel syndrome (IBS) whose long-term goal is to identify physiological and psychological mechanisms for the symptoms of abdominal pain and altered stool frequency in IBS. Experiment I tests the hypothesis that there are two subgroups of patients currently diagnosed IBS, one of which has a physiological basis for bowel symptoms (henceforth designated IBS) and the other primarily a psychological basis (henceforth designated functional bowel disorder or FBD). IBS patients who meet criteria intended to identify those with a physiological basis for symptoms will be compared to patients with FBD (defined by abdominal pain plus altered bowel habits) and to asymptomatic controls. A second hypothesis is that the incidence of peristaltic contractions/24 hrs determines whether patients report constipation or diarrhea but does not correlate with the distinction between IBS and FBD. Half of the IBS group and half of the FBD group will have constipation as a predominant symptom and half will have diarrhea as a predominant symptom. Dependent measures for Experiment I are (1) incidence of colon EMG slow waves greater than equal to 15 sec in duration. (2) contractile activity in the colon (motility index) for 24 hours, and (3) number of peristaltic contractions in 24 hours. Experiment II tests the hypothesis that subjects with FBD who have not consulted a physician, by comparison with IBS nonconsulters, will score higher on psychometric measures of neuroticism and on scales measuring childhood reinforcement of bowel complaints. Additional hypotheses are that consulters with IBS and FBD will score higher than nonconsulters with these diagnoses on measures of childhood reinforcement for somatic complaints, and that consulters will use the coping styles of information seeking and support seeking more often and denial less often than nonconsulters. These hypotheses will be tested by administering psychometric inventories to approximately 600 women clients of Planned Parenthood clinics and by providing physical examinations to those with bowel symptoms. The relationship of stressful life events to exacerbations of bowel symptoms will be studied prospectively by administering a Scale of Life Events, a symptom inventory, and a questionnaire about medical clinic visits and disability days quarterly for the year.